Half a hosepipe
| Stonehenge | 51 10 43.88N 01 49 34.38W | The picture is several years old; I understand that the road which cuts across the side has now been removed! |
In the first lesson of the Digging in Bible Lands course, available without cost from our website, we discuss some of the techniques of archaeology, a necessary first step so that we can appreciate some of the discoveries that have been made by archaeologists.
Some of the techniques, such as aerial photography or side-scanning radar are fairly high-tech and were not available to the earliest archaeologists, but there is one technique which has proved its usefulness time and again and which was used by early archaeologists and that is crop markings. Curiously, it also appears to engender confusion in some of the students.
The theory behind the technique is very simple: any change in the soil has the potential to produce a change in whatever grows in the soil. Take, for example, the common sight of tractor wheel marks running across a field of grass or wheat. You may think that the farmer has carelessly driven his tractor through the crop of wheat, crushing the growing plants beneath his wheels, but in many cases what has actually happened is that the farmer drove his tractor across the field before the crop began to grow. The weight of the tractor compressed the soil and the seeds in this compacted soil have struggled to grow - they have had to work harder to force their way through the soil, rainfall runs off instead of soaking in, and so on. By the time the crop is grown, the wheel marks are distinguished by stunted plants!
Of course sometimes the opposite can happen. Sir Mortimer Wheeler once made a name for himself by walking across a piece of waste ground and marking the site of tombs. There was nothing visible on the surface - no indentations, no humps or bumps, yet in every spot he had marked, a tomb was found. His secret? He noted a particular plant which he knew had long roots and was most unlikely to flourish in the shallow soil of the desert site. Wherever this plant was growing, he reasoned, there must be deeper soil and that implied the presence of a grave!
Back in the 1970s I happened to drive past an excavation in Essex and curiosity led me to stop and ask what was going on. It turned out that they were excavating a hill fort which had only been revealed by the particularly hot and dry summer of that year.
"Yes, but how did you know it was here?" I asked.
The young man to whom I was talking led me over to where a swathe had been cut through the wheat and pointed. I was astonished to see a belt of tall, green wheat some ten feet wide running in a huge circle across the field. On either side the wheat was much shorter and yellower in appearance.
"That's the ditch," the young man told me. "It's been filled in over the years but the deep ditch dug in the chalk holds the water, producing taller and greener plants than those growing on the relatively shallow soil where there was once a bank."
Crop markings are usually best observed from the air - which may mean an aeroplane or merely a convenient hill overlooking the site! Sometimes you can see the outlines of vanished buildings in a field, for the soil over the buried walls is shallower than the soil outside the walls and the crops are affected accordingly.
Last year - 2013 - we in Britain enjoyed a long, hot summer and the water companies put out their usual doomladen predictions that the water was about the run out and hosepipe bans were announced and enforced. Fields all over the country turned yellow as the lack of rainfall affected the plants. Gardeners in tourist sites rushed to pull out their hoses and keep the gardens green and the tourist pounds flowing.
Among these tourist sites was Stonehenge on the Salisbury Plain. Rightly or wrongly, the people in charge felt that tourists might feel cheated at seeing the famous stones rising out of an acre of dead grass and the groundskeeper, a Mr Tim Daw, was ordered to get out the hosepipe and see to it. Unfortunately, Stonhenge is run by English Heritage, a government body whose main aim appears to be charging tourists as much as possible while spending as little as possible on maintenance and other expenses. The result was that when Mr Daw got out his hose, he discovered that the cheeseparing management had provided him with one that was half an acre too short! Try as he might, he could only water half the monument; in half the monument the grass was green and lush, in the other half the grass was parched and yellow. Presumably that was the half out of sight of the viewing platform and so Mr Daw's appeal for a longer hose was ignored.
It turns out, however, that Mr Daws was a conscientious individual and as the summer wore on and the unwatered part of the site grew ever more yellow, he fretted over it until one day, as he stood on the public path looking at the patchy and blotchy grass it suddenly dawned on him that the patches were not as random as he had supposed. They were, in fact, in the shape of a circle.
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| In this aerial photograph you can clearly see patches of less green grass which may mark the position of long-lost stones. |
If you use Google Earth and go to the coordinates given at the head of this article, you will see that the stones only form half a circle and apparently there has been considerable debate over the years as to whether the missing half of the circle ever existed or whether it was planned to be a semi-circle. Archaeologists have carefully examined the ground in the hope of finding ancient pits or holes that would settle the question, but without success. However it stands to reason that the soil beneath several tons of Welsh granite will be more compacted than the soil next to it and that might very well be reflected in the amount of water the soil could retain.
Daws reported his observation to the management of the site and they called in Susan Greaney, an in-house archaeologist employed by English Heritage. "A lot of people assume we've excavated the entire site and everything we're ever going to know about the monument is known ... but actually there's quite a lot we still don't know and there's quite a lot that can be discovered just through non-excavation methods," Ms Greaney said.
Unfortunately his keen eyes may not bring Mr Daws a longer hose. In fact, they may result in the loss of his existing hose, as Ms Greaney is, apparently, keen to see what might be discovered in the other half of the site and is talking about suspending all watering of Stonehenge. Unfortunately, she might have to wait for the weather to cooperate, because if nature supplies the lack of irrigation, there will be no crop markings to see.
© Kendall K. Down 2014
